Method for bending and straightening a cast bar and plant for carrying out such method

ABSTRACT

The invention relates to a method for bending and straightening a cast bar issuing from a stationary, curved bar guiding means of a continuous casting plant, using a bending and straightening apparatus comprising at least two bending and straightening rolls and a reaction roll, and, if desired, pulling rolls, in which the improvement resides in that the bending roll following the reaction roll is readjusted in dependence on a deviation from a desired pressure valve which is given when the cast bar is free from bending moments, the pressure being indicated by at least one pressure gauge arranged behind the bending apparatus, in order to offset the deviation from the desired value, whereupon, in cast this measure is not effective, the bending rolls are slewn around a horizontal rotation axis in a direction contrary to that in which said bending roll is readjusted, which measure guarantees that absolutely no bending moments are exerted on the cast bar leaving the bar guiding means in the area before the reaction roll nor on the bent and straightened cast bar leaving the last bending roll.

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[54] METHOD won BIENMNG AND 2,391,419 12/1945 1101a ..72/l63S'llMMGH'lFENliNG A CAST WAR AND g tgg w 9911999 Wt ztztztitfizztrgtittiimm111M011 72] Inventor: RudolfSeholiEmnnn,Linz,Austria 1 [73] Assignee: Vereinigte OsterreichischelEiStBllll-llllllld T ntion relates to a method for bending and f fStahlwerllre Ahtiengmellschnlit, Ling, Ausmg a cast bar lssulng from a ycurved bar guldmg m means of a continuous casting plant, using a bendingand straightening apparatus comprising at least two bending and [22]Filed: July 23, 1970 straightening rolls and a reaction roll, and, ifdesired, pulling [21] Appl' No: 57,455 rolls, in which the improvementresides in that the bending roll following the reaction roll isreadjusted in dependence on a deviation from a desired pressure valvewhich is given when Foreign Allltlliwtiolll r y Dam the cast bar is freefrom bending moments, the pressure being July 25, 1969 Austria ..A7190/69 gi gffig gg fifi sfigffi f fizi' ig gg iiflg gx $2 [58] W111 oliSearch ..72/160-165,19 gg m figggf mgfg z f gggigg$53353 [561 mmmmt$232531: 5131111032 31: ffiti ir'ii li iififilfihi ififi UNITED STATESPATENTS straightened cast bar leaving the last bending roll.

2,091,789 8/1937 Maussnest ..72/l65 X 11 Claims, 2 Drawing FiguresINVENTOR. RUDOLF SCHEJFFMANN M ym l his I ATTORNEYS MlETllllUlD FURIBENDTNG ANll) S'llttAllGlll'llENllhlG A CAST BAR AND lPlLAN'lf lFUllttCAEtRYllNG UlU'lF SlUtClill lVllE'lIlillUlDt The invention relates to amethod for bending and straightening a cast bar issuing from astationary, curved bar guiding means of a continuous casting plant bymeans of a bending and straightening apparatus comprising at least twobending and straightening rolls and a reaction roll; and to a plant forcarrying out such method.

it is desired to keep the construction height of continuous castingplants low; therefore, in so-called curved plants, curved supporting andguiding means are arranged in succession to the casting mould, and theguiding means are, in turn, followed by bending and straighteningapparatuses so that the cast bar may run out either horizontally andstraight or in an inclined plane. After the cast bar has been bent andstraightened, it may be guided on by a curved roller table or in aroller guide which may be advantageous when hollow bars are cast.

The bending and straightening apparatuses that have been used so farhave various disadvantages; above all the bending forces acting upon thebar in front of and behind the bending and straightening zone propercreate bending moments which cause the cast bar to be torn. If thesebending moments act upon the bar in the area between the end of thestationary bar guiding means and the bending and straighteningapparatus, cracks may occur at the bar surface or existing cracks may beenlarged. Also the bar guiding means may be overstressed; therefore theconstruction of the bar guiding means had to be very solid, i.e.overdimensioned. When bending moments act upon the bar where it issuesfrom the bending and straightening apparatus, the bar may likewise becracked and/or deformed, e.g. distorted or warped. These disadvantagesof known plants for bending and straightening cast bars becomeparticularly obvious when the core of the cast bars is still liquid.

The invention is aimed at creating a method and a plant for bending andstraightening a cast bar in which the cast bar remains free from bendingmoments in front of and behind the bending and straightening zone andwith which the described disadvantages of the known plants are avoided.

The method according to the invention for bending and straightening abar issuing from a stationary, curved bar guiding means of a continuouscasting plant by means of a bending and straightening apparatuscomprising at least two bending and straightening rolls, a reaction rolland, if desired, pulling rolls, is characterized in that the bendingroll following the reaction roll is re-adjusted in dependence on adeviation from a desired pressure-value as indicated by at least onepressure gauge arranged behind the bending apparatus and sensing bendingmoments acting upon the cast bar, in order to off-set the deviation fromthe desired value, whereupon, in case this measure is not effective, thebending rolls are slewn around a horizontal rotation axis in a directioncontrary to that in which said bending roll is re-adjusted, whichmeasure guarantees that absolutely no bending moments are exerted on thecast bar leaving the bar guiding means in the area before the reactionroll nor on the bent and straightened cast bar leaving the last bendingroll.

Preferably the bending apparatus including the reaction roll, thebending rolls and the pulling rolls is slewn as a unit.

The invention further relates to a plant for carrying out the methodcomprising at least two bending and straightening rolls capable of beingindividually tightened, a reaction roll, and, if desired, pulling rolls,which plant is characterized in that the bending rolls are slewablearound a common horizontal axis,

Preferably, the reaction roll, the bending rolls and the pulling rollsare united in a common stand, the stand being slewable in relation tothe foundation.

Suitably the slewing axis of the stand is arranged in the vicinity ofthe reaction roll axis so that, when the stand is slewn, the relativemovement of the reaction roll takes place about tangentially to the castbar.

Further features of the invention are the following: the slewing devicefor the stand is arranged at that side of the stand from where the barissues; the pressure gauge is built in between the stand frame and theslewing device; at least one pair of the bending rolls and thecorresponding pulling rolls are formed as shaping rolls so that thestand is designed as a combined pulling, straightening and rollingstand. The bending rolls and the pulling rolls may be drivenindividually and hydraulically tightened.

in order that the invention may be more fully understood an embodimentthereof shall now be explained by reference to the accompanyingdrawings, in which FIG. l is a vertical sectional view and FIG. 2 is afront view, partly in section, of a combined pulling, straightening androlling stand.

The cast bar ll leaves the stationary, curved bar guiding means 2 havingthe radius R and is guided into the pulling, straightening and rollingstand 3, where it is bent into horizontal direction and subsequentlydrawn out. The cast bar 1' which is bent into horizontal direction istransported on in horizontal direction over a stationary roller table 9.

In the stand 3 the reaction roll 4, the bending and straightening roll5, the pulling roll 6, the pulling roll 7 and the bending andstraightening roll 8 are arranged in a stand frame 15 designed in twoparts. The rolls are mounted in insert pieces denoted with numerals 10,ll, 112, B3 and M, Numeral 1o denotes a releasable cap connection, andnumerals W, W, 19 denote the cross connections for the stand frame 15.The reaction roll 41 may be actuated by a mechanical adjustment device20 for adaptation to varying bar thicknesses. The rolls 5, 6 and 8 arehydraulically tightened by means of devices 21, 22, 23. The bendingapparatus including the reaction roll 4, the bending rolls 5, 8 and thepulling rolls 6, 7 is slewable as a unit; pins 24 25 which are arrangedhorizontally on the frame are inserted into bearing lugs 24a, 25a whichare cast integral with the frame and mounted in bearings 24!), 25b ofbearing blocks Me, 25c fixed to the foundation 30. The axis 26 of thepins 2A, 25 lies parallel to and near the axis of the roll A. A console27 is provided at the delivery side of the frame 15 which console servesto support the stand 3 against an adjustment means 29 fixed to thefoundation 30. A pressure gauge 28 is built in between the console 27and the slewing device 29.

An adjustable guiding means 3i is provided for introducing the cold bar.Numerals 32, 33 denote spacers which serve to support the insert piecesll, 12 and l3, M, respectively and, when the stand is used eg as rollingstand, to maintain an equal distance between the rolls during operation.

In the following it is explained how the plant functions. Between therolls A and 8 the roll 5 is arranged below the cast bar 1 which roll 5can be moved towards the cast bar in vertical direction so that owing tothe co-action of the three rolls 4, 5 and it the cast bar ll curved withradius R is bent to become the cast bar l with the radius R= which baris then conveyed on over the roller table 9.

When the roll 5 is moved vertically in upward direction the curve of thecast bar l is changed in the area between the rolls 4i and 8 andfurthermore the angle 01 is changed which is enclosed by the cast bar 1and the horizontal line in the area of the roll 4. Owing to the factthat in front of the roll 4 a rigid stationary bar guiding means 2 isarranged, the angle 0: cannot freely be changed so that undesiredbending moments act upon the cast bar l in the area before the roll 41;these bending moments cause uncontrolled forces which on the one handare exerted upon the bar guiding means and on the other hand areresponsible for the cast bar being torn unless specific measures aretaken to avoid these shortcomings.

Any moment acting upon the cast bar 1 on account of the bar guidingmeans 2 and from said cast bar via the rolls 4i, 5 and 8 upon the stand3 is registered according to the invention by a pressure gauge 28. Thispressure gauge 28 which is built in between the console 27 of the standframe 115 and the adjustment means 29 thus indicates those forces whichoccur outside the bending area proper. The pressure gauge 28 and theadjustment means 29 for slewing the stand 3 around the pins 24, 25should be arranged at a location as far as possible away from the pins24, 25 so as to ensure an adequate sensibility of the pressure gauge.

The pressure gauge 28 is adjusted in a manner that e.g. its desiredvalue (zero value) corresponds to an ideal operational condition, inwhich the cast bar 1 in the area between the bar guiding means 2 and theroll 4, and the bent cast bar 1 in the area between the roll 8 and theroller table 9 remain free from bending stresses.

According to the invention a deviation from the desired value indicatedby the pressure gauge 28 is used for changing the position of the rolls5, 8 in relation to the bar 1, until the desired value (zero value) isreached again, i.e. until the bar guiding means 2 is free from bendingmoments. The position of the roll 4 remains practically unchanged inthis process.

When the cast bar 1' leaves the plant according to the invention inrelation to the roller table 9 in a manner that it either is lifted awayfrom the roller table or that it is pressed onto it, further bendingmoments will occur in the area between the roll 8 and the roller table9. These bending moments, too, cause the pressure gauge 28 to indicate adeviation from the desired value (zero value) to plus or minus values.

By displacing the roll 5 in vertical direction the cast bar 1 may beadapted to the shape and position of the roller table 9 in a manner thatthese bending stresses are eliminated and the indicator of the pressuregauge 28 again shows the desired zero value; then the roller table 9 isloaded only with the own weight of the bent cast bar 1'.

in operation, when the pressure gauge 28 indicates a value other thanzero, it is at first unknown where the bending moments acting upon thebar come from: from the area between the bar guiding means 2 and theroll 4 and/or from the area between the roll 8 and the roller table 9.

When the pressure gauge 28 indicates a deviation from the desired zerovalue at first an automatic control for the vertical adjustment of theroll 5 is actuated. (Such controls are known per se and therefore nofurther explanation need be given here of them). When, upon displacementof roll 5, the pressure gauge again indicates the desired zero value,the deviation had been caused by a bending moment behind the roll 8. If,however, the deviation from the desired zero value is aggravated by thismeasurei.e. when the indicator deflects in the wrong sense-then thedeviation had been caused by a bending moment in front of the roll 4. Inthis case the automatic control works as follows: as soon as a marginalvalue, i.e. a predetermined maximum deviation from the desired zerovalue, is transgressed, the slewing device 29 is additionally actuated,which device is preferably designed as hydraulically operable cylinder.The adjustment device 29 serves to slew the stand 3 around thehorizontal axis 26 in a direction contrary to that in which the roll 5had been displaced and with greater speed so that the displacement ofthe roll 5 which had been carried out in the wrong direction is rapidlyremedied. Thus, the correct measure is initiated by slewing the stand 3and when the pressure gauge 28 again indicates the desired zero valuethe displacement of the roll 5 and slewing of the stand 3 is terminated.

If, e.g., the pressure gauge 28 suddenly indicates plusvalues, thereason for this deviation may be two fold. The rolls 5, 8 may standhigher than would be appropriate for the bending line; then a moment iscreated in the bar guide 2 which exerts additional forces on the roll 5.Also, it may be possible that the bar 1 leaving the plant according tothe invention is insufficiently straightened and therefore is lifted offthe roller table 9; then, too, a moment is created which is indicated asa pressure increase by the pressure gauge 28. The automatic control atfirst causes the roll 5 to be lifted. If after this measure theindicator does not go back to the desired zero value and the pressure isfurther increased, the rolls 5, 8 had been positioned too high inrelation to the bending line. As soon as the indicator transgresses apredetermined marginal value, the

stand 3 is additionally slewn in downward direction contrary to themovement of the roll 5; by this measure a bending moment which onaccount of the bar guiding means 2 had acted upon the cast bar 1 and hadcaused the deviation of the pressure gauge 28 is gradually reduced untilthe bar 1 is free from bending stresses. If, however, the deviation hadbeen caused by the bar being insufficiently straightened, the indicatorwill be brought back to the desired zero value simply by moving the roll5 in upward direction; in this case it is not necessary to slew thestand.

If on the other hand the pressure gauge 28 indicates minus values, i.e.a pressure decrease or relief from load of the stand, the automaticcontrol would obviously effect a lowering of the roll 5 and later, ifthis measure should prove to be wrong, slewing of the stand 3 in upwarddirection until the indicator goes back to the desired zero value.

The invention is also applicable when more than two bending andstraightening rolls 5, 8 are provided. It is also possible to employseveral pressure gauges for controlling the re-adjustment when the stand3 is supported against the foundation 30 at several points.

The described automatic control of the movement of the roll 5 and of theslewing movement of the stand 3 may be employed with particularadvantage in the combined pulling, straightening and rolling stand whichis illustrated in the drawing. The pulling rolls 6, 7 for drawing thebar are coordinated to the bending rolls 5, 8. The rolls 5, 6 aredesigned as shaping rolls so that the cast bar may be shaped immediatelyafter its solidification. The rolls 7, 8 may likewise be designed asdeformation rolls, either alone or in addition to the rolls 5, 6. Whenthe upper and lower side of the cast bar 1 have different temperaturesthe shaping rolls 5, 6 will displace themselves in vertical directionbecause the roll engaging with the warmer bar side will enter moredeeply into the material. As a result thereof, forces are exerted on thebar guiding means 2, the pressure gauge 28 indicates a deviation fromthe desired zero value, and the automatic control starts to functionuntil a readjustment of the roll 5 is effected. Obviously, the upperroll 6 is automatically moved together with the lower roll 5 since thespacers 32 guarantee a constant distance between the rolls 5, 6.

What I claim is:

1. In a method for bending and straightening a cast bar in a continuouscasting plant, comprising passing said bar leaving a stationary curvedbar guiding means through a bending and straightening apparatusincluding a reaction roll and at least two bending rolls, the steps ofre-adjusting one of said bending rolls following said reaction roll assoon as at least one pressure gauge arranged behind said bending andstraightening apparatus and adapted for sensing bending moments actingupon said cast bar indicates a deviation from a desired value so as tocancel said deviation and, in case said re-adjustment remainsineffective, slewing said bending rolls around a horizontal axis in adirection contrary to that in which said bending roll has beenreadjusted in order to keep said cast bar free from bending moments bothwhen it passes from said guiding means to said reaction roll and when itis delivered from the last bending roll in bent and straightenedcondition.

2. The method set forth in claim 1, wherein said bending andstraightening apparatus including said reaction roll, said at least twobending rolls and any additional pulling rolls is slewn as a unit.

3. Apparatus for bending and straightening a cast bar in succession to acontinuous casting plant having a stationary, curved bar guiding means,comprising a reaction roll and at least two bending rolls, at least onepressure gauge arranged behind said bending rolls and adapted toregister bending moments acting upon said cast bar leaving saidstationary curved bar guiding means in the area before said reactionroll and on said bent and straightened cast bar leaving the last bendingroll, which bending moments are indicated as deviations from a desiredvalue, means for re-adjusting one of said bending rolls which isarranged behind the reaction roll in response to deviations tending torestore said desired value, and a slewing device for slewing said atleast two bending rolls around a common horizontal axis in a directioncontrary to that in which said one bending roll is re-adjusted.

4. The apparatus set forth in claim 3, wherein said apparatus furtherincludes pulling rolls.

5. The apparatus set forth in claim 3, wherein said reaction roll, thebending rolls and any additional pulling rolls are united in a commonstand, the stand being slewable in relation to a foundation.

6. Apparatus for bending and straightening a cast bar in succession to acontinuous casting plant having a stationary curved bar guiding means,comprising a stand of horizontal rolls including a reaction roll nearbar input side of said stand, at least first and second bending rolls,and a number of pulling rolls mounted in a common frame, at least onepressure gauge adjacent to bar output side of said stand, adapted toregister bending moments acting on said bar on either side of said standas deviations from a desired value, means for readjusting said firstbending roll in response to deviations, tending to restore said desiredvalue, and means for slewing said stand around a horizontal axisarranged in the vicinity of the reaction roll axis so that slewing ofsaid stand will produce a relative movement of said reaction roll in adirection substantially tangential to said cast bar.

'7. The apparatus set forth in claim 6, wherein the slewing device forthe stand is arranged at the bar output side of the stand.

8. The apparatus set forth in claim 6, wherein the pressure gauge isbuilt in between the frame of the stand and the slewing device.

9. The apparatus set forth in claim 6, wherein at least one pair of thebending rolls and the corresponding pulling rolls are designed asshaping rolls so that the stand is operable as a combined pulling,straightening and rolling stand.

The apparatus set forth in claim 6, whereirrthe bending rolls and thepulling rolls are driven individually.

11. The apparatus set forth in claim 6, wherein the bending rolls andthe pulling rolls can be tightened hydraulically.

1. In a method for bending and straightening a cast bar in a continuouscasting plant, comprising passing said bar leaving a stationary curvedbar guiding means through a bending and straightening apparatusincluding a reaction roll and at least two bending rolls, the steps ofre-adjusting one of said bending rolls following said reaction roll assoon as at least one pressure gauge arranged behind said bending andstraightening apparatus and adapted for sensing bending moments actingupon said cast bar indicates a deviation from a desired value so as tocancel said deviation and, in case said re-adjustment remainsineffective, slewing said bending rolls around a horizontal axis in adirection contrary to that in which said bending roll has beenreadjusted in order to keep said cast bar free from bending moments bothwhen it passes from said guiding means to said reaction roll and when itis delivered from the last bending roll in bent and straightenedcondition.
 2. The method set forth in claim 1, wherein said bending andstraightening apparatus including said reaction roll, said at least twobending rolls and any additional pulling rolls is slewn as a unit. 3.Apparatus for bending and straightening a cast bar in succession to acontinuous casting plant having a stationary, curved bar guiding means,comprising a reaction roll and at least two bending rolls, at least onepressure gauge arranged behind said bending rolls and adapted toregister bending moments acting upon said cast bar leaving saidstationary curved bar guiding means in the area before said reactionroll and on said bent and straightened cast bar leaving the last bendingroll, which bending moments are indicated as deviations from a desiredvalue, means for re-adjusting one of said bending rolls which isarranged behind the reaction roll in response to deviations tending torestore said desired value, and a slewing device for slewing said atleast two bending rolls around a common horizontal axis in a directioncontrary to that in which said one bending roll is re-adjusted.
 4. Theapparatus set forth in claim 3, wherein said apparatus further includespulling rolls.
 5. The apparatus set forth in claim 3, wherein saidreaction roll, the bending rolls and any additional pulling rolls areunited in a common stand, the stand being slewable in relation to afoundation.
 6. Apparatus for bending and straightening a cast bar insuccession to a continuous casting plant having a stationary curved barguiding means, comprising a stand of horizontal rolls including areaction roll near bar input side of said stand, at least first andsecond bending rolls, and a number of pulling rolls mounted in a commonframe, at least one pressure gauge adjacent to bar output side of saidstand, adapted to register bending moments acting on said bar on eitherside of said stand as deviations from a desired value, means forreadjusting said first bending roll in response to deviations, tendingto restore said desired value, and means for slewing said stand around ahorizontal axis arranged in the vicinity of the reaction roll axis sothat slewing of said stand will produce a relative movement of saidreaction roll in a direction substantially tangentiaL to said cast bar.7. The apparatus set forth in claim 6, wherein the slewing device forthe stand is arranged at the bar output side of the stand.
 8. Theapparatus set forth in claim 6, wherein the pressure gauge is built inbetween the frame of the stand and the slewing device.
 9. The apparatusset forth in claim 6, wherein at least one pair of the bending rolls andthe corresponding pulling rolls are designed as shaping rolls so thatthe stand is operable as a combined pulling, straightening and rollingstand. 10 The apparatus set forth in claim 6, wherein the bending rollsand the pulling rolls are driven individually.
 11. The apparatus setforth in claim 6, wherein the bending rolls and the pulling rolls can betightened hydraulically.